She has been targeted on a number of occasions (Image: Media Wales Ltd)

"I’ve gone from someone hyper-confident, carefree, going from one thing to another, never looking over my shoulder. Now I look over my shoulder mentally and physically.”

Speaking on the show, which is set to be aired this week, Sian said the stalker was present at a rally event where she had been presenting awards.

After returning to her Mid Wales home she was appalled by what she found.

“Having driven up from London with my husband there were loads of letters and right on top was a handwritten letter,” she said.

Sian Lloyd (Image: Media Wales Ltd)

The stalker has not been found (Image: S4C)

“I opened it and a picture fell out of the most revolting close up of what we shall say was a man in a state of excitement, a man’s private parts, and it could not have been a bigger close-up.

“And there was an accompanying letter that said ‘This is for you and there’s plenty more where that came from’ and he even gave his phone number.”

Despite leaving the phone number police were unable to trace the culprit.

She added: “I resent his intrusion enormously. You could say he’s done me a favour as I’m incredibly alert because of what could go wrong, and it might sound as if I’m a scaredy-cat or paranoid but better that than the possibility of a tragic outcome.”